This R13 is to request support for the 53rd Annual Meeting of the Society for Leukocyte Biology (SLB) entitled ?Host-Microbial Interactions in Health and Disease: The Good, the Bad and the Ugly? to be held in Portland, OR from September 30-October 3, 2020. SLB is the leading scientific society with a focus on leukocytes and their roles in the pathophysiology of acute and chronic diseases. No other scientific meeting regarding study of the immune system focuses on the leukocyte with the breadth and depth of SLB so the annual meetings sponsored by SLB fill this void. Funds derived from this proposal will be distributed in the form of travel awards that will provide much needed assistance to the ability young investigators and trainees to attend. The essential goals of the annual meeting include: 1) advancing original research and related scientific endeavors in the field of leukocyte biology and host defense, 2) promoting the career development of junior and new investigators interested in leukocyte biology, 3) disseminating information about the field to the wider scientific and lay audience, and 4) encouraging the translation of basic research in leukocyte biology to applications in the clinic. The Co-Chairs of the 2020 meeting are Ilhem Messaoudi, University of California, Irvine and Louis Justement, University of Alabama at Birmingham and they have put together a meeting agenda to meet these goals through three Specific Aims. Aim 1: To better understand the bidirectional host:microbe interactions as they relate to immune health and disease. To meet this objective, the meeting will bring together speakers who look at the impact of the microbiome on the host immune system, the mechanisms that are employed by the host to respond to and control pathogenic microbes, and the signals derived from commensal microbes that regulate immune function. The agenda will include a total of 4 Plenary Sessions and 8 Concurrent Sessions with a total of 19 invited speakers. There will also be 4 poster sessions, and a Poster Flash Talks session highlighting selected abstracts. Aim 2: To provide an opportunity for new investigators and student trainees to interact closely with established scientists. A significant innovation for the 2020 meeting will be the SLB-SCHOOL (Society for Leukocyte Biology-Symposium for Career development and Hands-On Opportunity to Learn) which will offer trainees a full day instructional workshop covering topics related to research regarding the microbiome. The expectation is that enrollees will gain practical insight into this topic and more actively participate with experts in the field. Aim 3: To promote diversity and inclusion in the field of leukocyte biology by cultivating the participation of women, underrepresented groups, early stage investigators and disadvantaged individuals. The Diversity, Equity and Inclusion (DEI) committee will sponsor workshops and awards to encourage the participation of women and scientists from underrepresented groups. In sum, the 2020 program is purposefully designed to enhance awareness of the influence of leukocyte biology in health and disease and inspire young investigators.